Functional Anatomy of the Nose

Question 1

Describe the functions of the nose

Answer 1

• Sense of smell
• Provides a route for inspired air
• Filters inspired air - trapping particles in nasal hair or mucous
• Moistens and warms inspired air
• Resonating chamber for speech

Question 2

Explain the structure of the external nose

Answer 2

• Inspired air enters via vestibule of external nose
• External nose contains sebaceous glands and hair to trap big particles entering nose
• External nose formed from bone and cartilage
  - Upper part made of nasal bone and maxilla

Question 3

Describe the lining of the nose

Answer 3

• External nose is lined with skin
• Nasal cavity is lined with mucous membrane
• Olfactory mucous membrane located on the top near the cribriform plates
  
  • Contains olfactory nerve
• Respiratory mucous membrane everywhere else and lined with pseudostratified columnar ciliated epithelium

Question 4

Describe the functions of the nasal cavity

Answer 4

• Filters (mucous/cilia)
• Humidifies (watery secretions)
• Warms (rich blood supply)
• Nasal cavity has large surface area compared to nostril to slow down airflow and increase time for filtering, humidifying and warming
• Drainage from paranasal sinus and nasolacrimal duct (drains eye)
  
  • Get runny nose when crying

Question 5

Describe the boundaries of the nasal cavity

Answer 5

• Lateral wall - conchae and maxilla bone
• Floor - formed from hard palate - maxillary and palatine bone
• Roof - frontal bone, ethmoid-cribriform plate, nasal bone and sphenoid bone
• Medial wall
  
  • Made of nasal septum and septal cartilage
  • Nasal septum made of ethmoid and vomer bone

Question 6

State the paranasal sinuses in the head

Answer 6

Frontal, ethmoid, sphenoid, maxillary

Question 7

Describe the function of the paranasal air sinues

Answer 7

• Air filled spaces that are extensions of nasal cavity
  
  • Absent at birth
• Lined with respiratory mucosa - ciliated and secrete mucous
• Help humidify and warm inspired air
• All drain into the nasal cavity via small channels called ostia into a meatus

Question 8

Describe conchae and meatuses

Answer 8

• Contains conchae - 3 bony projections known as superior, middle and inferior
  
  • Slows airflow by causing turbulent airflow
  • Increases surface area over which air passes
• Meatuses located in-between conchae and between inferior conchae and nasal cavity floor
  
  • Have holes where paranasal air sinuses drain into nasal cavity

Question 9

Describe the anatomical relations of the paranasal sinus

Answer 9

• Important anatomical relations of the paranasal sinuses include the nasal cavity, orbit and anterior cranial fossa
• Roots of upper teeth can sometimes projects in maxillary sinus

Question 10

Describe the nerve supply to the nose

Answer 10

• Special sensation carried through olfactory nerve

- Trigeminal nerve supplies sensation to nose and nasal cavity

Question 11

Describe the blood supply to the nose

Answer 11

• Arterial supply to nasal cavity arises from branches of ophthalmic artery and maxillary artery
  
  • Arterial anastomoses in anterior septum (Kiesselbach’s plexus)
    
    • Most common source of bleeding in epistaxis
  • External carotid artery -> maxillary artery -> sphenopalatine artery
  • Internal carotid artery -> ophthalmic artery -> ethmoidal branches
• Venous drainage from nasal cavity into pterygoid venous plexus, cavernous sinus and facial vein
• Bleeding from the sphenopalatine artery can be very serious and difficult to treat

Question 12

Describe the management of epistaxis

Answer 12

• Pinch nasal septum cartilage and hold head forward
  
  • Prevent blood from entering stomach, which could cause vomiting and stomach pain
• If that fails, then cautery (burning vessels)
• If that fails, then anterior packing (nasal tampons)
• If that fails, then posterior packing (or even surgical interventions)

Question 13

Explain what a septal haematoma is

Answer 13

• Cartilaginous part of septum takes blood supply from overlying perichondrium
• Trauma to nose can lead to buckling of septum and shearing of blood vessels
• Blood accumulates between perichondrium and cartilage
• Present with swelling of nasal septum

Question 14

Explain what a saddle nose deformity is

Answer 14

• Untreated septal haematoma leads to avascular necrosis of cartilaginous septum
  
  • Septal haematoma needs to be drained to prevent this
• Can also develop infection in the collecting haematoma

Question 15

Explain what nasal polyps are and its symptoms

Answer 15

• Benign swellings of nasal mucosa
• Usually bilateral
• Pale or yellow in appearance
• Symptoms include:
  
  • Blocked nose and watery rhinorrhoea
  • Post-nasal drip
  • Decreased smell and reduced taste
  • Unilateral polyp and/or blood-tinged secretion may suggest tumour

Question 16

Explain what rhinitis is and its symptoms

Answer 16

• Inflammation of the nasal mucosal lining
• Symptoms include nasal congestion, runny nose (rhinorrhoea), sneezing, nasal irritation, postnasal drip
• Causes include simple infective rhinitis (viral - the common cold), allergic rhinitis

Question 17

Describe what acute sinusitis is and its symptoms

Answer 17

• An acute inflammation of lining of sinus
  
  • Commonly infective and often secondary to viral infection of nasal cavity (common cold)
• Maxillary sinus most commonly affected
  
  • Drainage of maxillary sinus at the roof of the sinus, so goes against gravity to drain
• Symptoms include non-resolving cold, pyrexia, blocked nose and rhinorrhoea, discharge, headache
• Can feel toothache as maxillary nerve provides sensation to upper teeth as well as maxillary paranasal sinuses

Question 18

Describe the pathophysiology of acute sinusitis

Answer 18

• Primary infection (eg. Rhinitis) leads to reduced ciliary function, oedema of nasal mucosa and sinus ostia and increased nasal secretions
• Drainage from sinus is impeded
• Stagnant secretions within the sinus become ideal breading ground for bacteria - secondary infection